Control of periodontitis requires elimination or suppresison of specific periodontal pathogens. To achieve this goal, knowledge is needed on the action of the currently employed therapeutic agents on specific periodontal pathogens. Oral spirochetes constitute possible periodontopathogenic organisms by virtue of their presence in elevated proportions in individuals with advanced forms of periodontal disease. The possibility therefore exists that oral spirochetes, or their products may contribute to the onset of periodontal disease. The aim of this research is to conduct a pilot study on the influence of fluoride on Treponema denticola. The action of fluoride on the growth of the organism as well as its effect on selected enzymes, particularly acid phosphatase, will be studied to determine the feasibility of this research project. The localization and purification of acid phosphatase as well as the interaction of fluoride with the purified enzyme will also be assessed. Finally, an attempt will be made to isolate fluoride- resistant mutants of T. denticola in order to assess the action of fluoride on their growth parameters and acid phosphatase. Knowledge obtained on the interaction of F and pertinent periodontopathogenic bacteria may lead to a rational approach for the treatment, or prevention of periodontitis.